1. Field of the Invention
Embodiments of the invention relate to medical imaging systems and, more particularly, to C-arm equipment.
2. Description of Related Art
C-arm medical imaging systems usually comprise an X-ray source and an X-ray detector, wherein the X-ray source and the X-ray detector are mounted on opposing ends of the C-arm gantry so that X-rays emitted by the source are incident on and detectable by the X-ray detector. The source and the detector are positioned so that, when an object (e.g., a human extremity) is interposed therebetween and is irradiated with X-rays, the detector produces data representative of characteristics of the interposed object. The data produced is displayed on a monitor or electronically stored.
C-arm equipment is used for surgical planning, co-registration, image fusion, navigation, implant fitting, surgical validation, etc. During these procedures, it is desirable to observe the patient from several different orientations and to do so without the need to reposition the patient. C-arm equipment has developed to meet these needs and is well known in the medical and surgical arts.
The C-arm is slidably mounted on a support assembly and defines an axis of rotation (perpendicular to the plane of the C-arm) about which the source and the detector are rotatable. By positioning this axis of rotation at or near an object, and by rotating the source and detector around the object in an orbital motion in the plane of the C-arm, images of the object taken at a plurality of different orientations can be obtained. These images can be combined to generate a comprehensive three-dimensional image of the object. The process of combining images to produce a comprehensive three-dimensional image is commonly performed with reconstructive software.
The C-arm is also typically rotatable on the support assembly, around a longitudinal axis parallel to the plane of the C-arm. By being rotatable about at least two different axes, the C-arm may be positioned at many different orientations in order to take images from different desirable perspectives. Thus, the mobile C-arm imaging machine greatly increases the efficiency and ease of taking images of a patient before and during a medical procedure.
C-arm imaging machines, such as those commercialized by GE Medical Systems (Innova®), can comprise a C-arm with a rotational axis offset relatively to the plane of the C-arm. The source and the detector are adjacent to the distal ends of the C-arm and are also offset from the plane of the C-arm, so that the axis of rotation of the orbital motion, as well as the longitudinal rotational axis of the C-arm, and the image axis intersect on a common point.
Such machines have the advantage of avoiding the complexity of other C-arm machines and of providing a large gap between the source and the detector. However, due to the offset, they present a large gantry volume and the range of movement of the C-arm around the longitudinal offset is limited.
Other C-arm imaging systems have a source and a detector, wherein the axis of the source and the detector extends in the median plane of the C-arm. Although this configuration authorizes smaller gantry volumes and a higher range of movement for the C-arm, the gap between the source and the detector is limited due to the height of the tube extending within the internal space of the C-arm.
Other C-arm equipment also use double slide rails to increase the imaging capacity of the machine. However, this equipment is of high complexity and gantry volume.
In view of the foregoing, there exists a need for C-arm imaging equipment that is of small volume, for use in operating or exam situations, and that provides a large gap between the source and detector, without being of complex structure, to allow the device to easily access a patient while enabling a wide range of movement and positions.